For me I only need look at their respective fights with Mosley. Mayorga was years past his best and notorious for not training and was bulling Mosley around until he ran out of steam very late.

Margarito on the other hand was seen as some sort of terminator in his prime coming off the battering of Cotto and Mosley kicked the fuck out of him.

If Mayorga had Margaritos work ethic in training there would be no question. Its only ever been his training and fight schedule that has let him down. He either wouldnt train properly or in the Mosley fight which I think he did train well for, he just had such long lay offs between action that he wouldnt really get in to any rythm for a few rounds then it was too late as he wouldnt have the right stamina to carry on.

The beating he took from Tito when he wasnt fit was unbelievable. Id say he has a better chin than Margarito too. I also doubt that Mayorga would lose to Santos. Margaritos only strength was his strength. His ability to boil down to welter. Like Hatton at light welter.